Circuit breakers of the kind having a magnetic blow-out



Dec. 3, 1957 A, LATOUR 2,815,418

CIRCUIT BREAKERS OF THE KIND HAVING A MAGNETIC BLOW-OUT Filed Feb. l3,v 1956 INVENTOR, .Hn db 8 L ac 0 ur United States Patent Ofiice 2,815,418 Patented Dec. 3, 1957 CIRCUIT BREAKERS OF THE KIND HAVING A MAGNETIC BLOW-OUT Andre Latour, Grenoble, France, assignor to Etablissements Merlin & Gerin, Grenoble, France Application February 13, 1956, Serial No. 565,248 Claims priority, application France February 25, 1955 6 Claims. (Cl. 200-147) This invention relates to circuit breakers of the kind having a magnetic blow-out, and has as one object a device which is intended to eliminate in each pole the conductor which connects the front arcing horn or one end of the front blow-out coil in the arc-extinction chamber to the blade or to the terminal corresponding to it and, as a second object, the use of such a device for the purpose of simplifying the means actuating the pneumatic blow-out device for the arcs forming on breaking.

It is known that in circuit breakers using magnetic blow-out the arm (which forms on breaking of the circuit between the fixed contact and the movable contact) moves, either under the action of thermal effects produced by it or under the action of a pneumatic blowout device, towards the inlet of the arc-extinction cham ber, where it operates to insert one or two blow-out coils into the circuit. Said coils then develop a magnetic field which forces the are into the chamber, where it is cooled and rapidly extinguished. In the case of a single coil, the arc jumps from the contacts onto two horns, one of which, disposed near the blow-out coil (rear arcing horn), is connected to one end thereof, and the other-disposed at the opposite end of the chamber (front arcing horn)is connected to the blade carrying the movable contact or to the terminal corresponding to said blade. In the case of two blow-out coils, disposed on either side of the chamber, one of the ends of the second coil, i. e. the coil most remote from the fixed contact, is connected by a conductor to the blade or to the terminal corresponding to this blade while the other end is connected to the front arcing horn. In either case the conductor may be rigid or flexible.

This conductor has the disadvantage that it maintains a permanent connection between the chamber which is live and the circuit which is dead. Another disadvantage of this conductor is that it interferes with the movement of the arm carrying the movable contact, particularly when it is desired to adopt a large opening angle for the purpose of rendering breaking visible, that is to say an opening position for which the movable contact has completely left the chamber and is situated at a certain distance from the latter, thus enabling the position of the circuit breaker to be seen without any possible mistake.

The object of the present invention is to obviate these disadvantages.

For the purpose of the first object, the present invention provide a device in which the electric continuity with the dead circuit is automatically eliminated after extinguishing of the arc.

For the purpose of the second object, the invention provides a device in which the. conductor which temporarily provides the electric continuity is physically moved from the path of the movable contact and taken to a point sufiiciently distance from the live parts to ensure isolation.

According to a preferred embodiment of the invention, the arm or blade carrying the movable contact is provided with an auxiliary pivoting blade which, during the opening movement and for a sufiiciently long interval of time, provides the connection which was previously provided by the eliminated conductor.

Another object of the invention is to render inoperative the electrodynamic forces capable of acting on the auxiliary blade when the circuit breaker is in the closed position, or when the break process has not terminated.

To this end the auxiliary blade is fixed in such manner on the main blade that during the closing movement it is inserted, by a sliding movement, between two stops which hold it firmly in place when the main blade is in the closed position or has not commenced to act on it during the opening movement.

In the accompanying drawings:

Figure 1 shows diagrammatically in side elevation and partly in section a circuit breaker with magnetic blowout having a single blow-out coil and provided with a connection device according to the invention, the circuit breaker being in the closed position.

Figure 2 is a similar view showing the position of the various elements of the device during the opening movement, and a few moments before the extinction of the arc.

Figure 3 is a vertical section taken on the line 33 in Figure 2, seen in the direction of the arrows.

Figure 4 is a side elevation showing of the various elements of the device in the break position of the circuit breaker.

Figure 5 is a similar view of a circuit breaker with two blow-out coils, the breaking elements being shown in the closed position and also in dotted lines in the break position.

In Figure 1, 11 is the frame of the circuit breaker on which is mounted the arc-extinction chamber 12 which contains a blow-out coil 13, a magnetic circuit or coil 14-, the cooling plates 15, a rear arcing born 16, and a front arcing horn 17. 18 is a contact clip which can receive the blade 29. The frame 11 also carries the input terminal 20, on which is mounted the fixed contact 22, and the output terminal 21, on which is fixed a support 26 carrying a spindle 25 about which the arm 24 can pivot. Said arm 24 carries on the one hand the movable contact 23 and on the other hand a fixed crosspiece 27 on which a blade 29 provided with a stop 30 is articulated at 28. A spring 31 tends to urge the blade 29 towards the arm 24. The blow-out coil 13 is inserted between the fixed contact 22 and the rear arcing horn 16 while the front arcing horn 17 is connected electrically by the conductor 34 to the clip 18, near which and on either side of which are disposed the stops 32 and 33.

The device operates as follows:

When the circuit breaker is closed, the various elements are situated in the position shown in Figure 1 and the current flows from 20, through 22, 23, 24, to 21. The blade 29 inserted in the contact clip 18 thus has no current passing through it.

At the moment of break, an arc is struck between 22 and 23, the left-hand root of said are immediately jumping from the fixed contact 22 to the rear arcing horn 16, so that the coil 13 is put into the circuit. When the movable contact 23 in its opening movement has come sufiiciently near to the horn 17, the right-hand root of the arc jumps from the movable contact 23 onto said front arcing horn 17 and the current then passes through the circuit: 20-1316arc1734-18292724- 21. This is shown by arrows in Figure 2. Continuing its opening stroke, the arm 24 comes to bear on the stop 30 and begins to act upon the blade 29. The arrangement of the various elements is so selected that, on the one hand, the arm 24 reaches the stop 30 always after the arc has been extinguished and that, on the other hand, following the rotary movement commenced by the arm 24 on opening, the blade 29 performs a translatory movement downwards, so as to be disengaged from the stop 33 when the arm 24 reaches the stop 39. Still continuing its opening movement, the arm 24 drives the blade 29 which then leaves the contact clip 18. The spring 31 keeps the blade 29 in contact with the arm 24 at stop and at the end of the opening stroke the arm and the blade are situated in the position which is shown in Figure 4, and in which there is no longer any connection between the arcextinction chamber and output terminal 21 of the circuit breaker.

On the re-closing, the arm 24 and the blade 29 turn in the counterclockwise direction. During this movement, while the arm 24 passes beside the clip 18, the blade 29 penetrates into said clip and advances until it is stopped by the stop 32. From this moment on, the arm 24 continues its closing stroke alone, until the movable contact 23 comes into contact with the fixed contact 22. During this movement the blade 29 performs a slight upward movement, due to the displacement of the crosspiece 2'7 consequent upon the rotation of the arm 24. it is then lodged between the stops 32 and 33 so that undesired opening of the blade, for example, by the electro-dynamic forces produced by a short-circuit current, is rendered impossible. The movable elements then again occupy the position shown in Figure 1.

Figure 5 shows a circuit breaker with two blow-out coils. Here the second coil is in circuit between the front horn 17 and the clip 18 and hence in the arc circuit when, on the break, the root of the arc jumps from the movable contact 22 to the horn 117. The operation of the device is the same as described hereinabove for the circuit breaker with a single blow-out coil.

In some cases it will be advantageous to dispose a blade 29 on either side of the arm 24 and two clips 18, connected in parallel, in the arc-extinction chamber. The arm 24 will then pass between the two clips and each blade 29 will engage in the corresponding clip 18.

It will be understood that the above description does not include the purely conventional mechanism by which the contact arm 24 is caused to open in response to circuit conditions, or under manual control. Such arrangements are well known to those skilled in this art, and the invention can be applied to any known circuit breaker construction within the limits already indicated respecting the use of magnetic blow-out and the horn gap.

While the invention has been described in connection with preferred embodiments given herein by way of illustration, it is to be understood that the details thereof can be varied without departing from the spirit of the invention as defined by the appended claims.

What is claimed is:

1. In a circuit breaker having magnetic blow-out in which the arc is developed for each pole between a first arcing horn connected electrically to one of the two terminals of the pole by the fixed contact, and a second arcing horn connected electrically to the other terminal of the pole, the improvement which comprises an auxiliary movable contact connected electrically to the main movable contact so as to remain electrically connected to the second arcing born when the main movable contact is in the closed position and during the break movement of the main movable contact until the arc is extinguished, but to be disconnected from the second horn as a consequence of the movement of the main movable contact.

2. A circuit breaker as claimed in claim 1, characterised din that disconnection of the auxiliary contact is effected by driving by the arm which carries the main movable contact, from a predetermined point of the opening stroke of the main movable contact.

3. A circuit breaker as claimed in claim 2, characterised in that the arm carrying the auxiliary contact is pivoted on the arm carrying the main movable contact and is elastically urged towards the arm carrying the main movable contact.

4. A circuit breaker as claimed in claim 3, characterised in that the arm carrying the auxiliary contact is arrested in the closed position in relation to the front arcing horn on the one hand by means of a first stop which arrests its movement in the direction or" the fixed contact and on the other hand by a second stop which arrests its movement in the opposite direction, the position of said second stop being such that by this means and as a consequence of the relative pivoting movement of the arm carrying the auxiliary contact in relation to the arm carrying the main movable contact during the opening movement of the main movable contact, the auxiliary contact is disengaged from said second stop at the moment when the arm carrying the main movable contact starts to drive the arm carrying the auxiliary contact.

5. A circuit breaker of the type provided with aredissipating horns, at least one magnetic blow-out coil cooperating therewith, one fixcd and one movable main circuit contact element, the movable contact element being pivoted to swing away from the fixed contact element to 01 en the main circuit, a contact clip, a conductive auxiliary blade pivoted upon said movable contact element upon an axis spaced from the pivotal mount of the latter and having its free end normally received by said clip, said main circuit contacts being arranged in a series circuit including said blow-out coil, said horns, and said clip, whereby an arcing circuit across said horns and coil is maintained during the opening movement of said movable main contact element via said clip and said auxiliary blade, and whereby the pivotal mounting of said auxiliary blade causes it to be drawn away from said clip by the final circuit-opening movement of said main movable contact element.

6. In a circuit breaker of the horn gap type having spaced breaker terminals and a main contact pivotally mounted on one terminal to close the circuit to the other terminal, a first arc horn mounted adjacent said other terminal and connected electrically thereto, a second arc horn spaced from the first arc horn and mounted adjacent the path of a part of said main contact during its circuit opening movement away from the said other terminal, and an auxiliary contact mounted on said main contact for maintaining said second arc horn in circuit with said main contact prior to and during the initial portion of the opening movement of said main contact, and to disconnect itself from said second arc horn during the final opening movement.

References Cited in the file of this patent UNITED STATES PATENTS 1,790,275 Lotz 2- Jan. 27, 1931 2,367,937 Gates Jan. 23, 1945 2,399,485 Harlow et al Apr. 30, 1946 2,597,257 Nye May 20, 1952 2,759,072 Rickert Aug. 14, 1956 FOREIGN PATENTS 590,970 Great Britain Aug. 1, 1947 

